How to Sterilize Fish Tank After Fish Died in 5 Steps

how to sterilize fish tank after fish died

It takes a lot of effort to create a healthy aquarium, but one day you wake up and find a dead fish in the tank. What are you gonna do?

Dead fish may cause water pollution that jeopardizes other aquarium creatures’ health. As a result, you have to remove the corpse of the dead fish and sterilize fish tank and equipment immediately. That will prevent the potential for the disease to spread.

But how to sterilize fish tank after fish died the right way? Keep reading!

Step-by-step to Disinfect Fish Tank After Fish Died


What to prepare

To clean a fish tank after a fish dies, here is what you need:

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  • A bottle of white vinegar
  • A bleach bottle
  • Fresh Water
  • Cleaning gloves
  • A sponge
  • A net to remove fish
  • Two buckets
  • A holding tank


Step 1: Take the dead fish out

The first step of cleaning the fish tank is removing the fish from the tank using a net.

You also can move the dead fish out of the tank by hand, but don’t forget to use long rubber gloves for your safety.

You then put dead fish in a bucket and dispose of it later.

What might happen if you don’t get rid of them soon? Dead fish can die of infectious diseases and spoil the water. This will harm other pets in the aquarium unquestionably. So, you better make it quick!

Step 2: Transfer and clean aquarium decorations

To clean and disinfect fish tank gravel effectively, you have to transfer all decorations, including gravel, or any things out of the tank. All of them also need to be sterilized before being returned to the tank.

You can use white vinegar to soak these decorations for at least 15 minutes. Cleaning aquarium decorations with vinegar is one of the economical ways to get rid of all the bacteria stuck on them at home.

Also, transfer your fish into a holding tank while you clean the aquarium.

Step 3: Use vinegar to clean fish tank


To clean ick out of a fish tank, you can use a mixture of vinegar and water with a ratio of 1:1.

After that, you can clean up all the surfaces inside the aquarium using a sponge. This mixture can remove algae or dirt accumulated on the tank walls.

To disinfect fish tank gravel effectively, vacuum it or put it into a bucket and rinse it under clean water.

However, remember to wash the sponge thoroughly each time cleaning up to reduce the spread of bacteria.

Step 4: Disinfect aquarium with bleach


A bottle of bleach is all that you need to disinfect the tank all by yourself at home.

Create a mixture of 1 part of bleach and 10 parts of water and wipe down the inside of the tank. Then use clean water to wash the fish tank thoroughly.

Disinfecting is an important step to killing all bacteria left in the water, it’s hard to be done without bleach.

Step 5: Add fresh-clean water

After sterilizing all the surfaces of your fish tank and all of its decorations, you now can refill clean water. However, you need to wait for around 24 hours to add the fish.

It’s common when your tropical fish tank is full of cloudy water after fish die. That is why we have to clean the tank and change the water.

Helpful tips/FAQs


What happens if you don’t get the dead fish out?

Fish died from ich or any reasons have to be removed as soon as possible. Why? The fish will quickly rot in the water that will pollute water and cause the spread of bacteria. That may be extremely dangerous to other fish and aquarium pets, in general.

So, if you see a dead fish in tank, don’t hesitate to remove it immediately.

How long does it take for a dead fish to decompose?

It may take about 7 to 10 days for a dead fish to break down totally. That’s why after betta fish died, it’s important to take it out immediately.

In fact, it will depend on how long your fish tank has been established. It may take about just 4 days to start the process of decomposing and bacteria takes care of the rest.

How often should I clean my fish tank?

You should clean your fish tank about once or twice every two weeks. Actually, the frequency of cleaning the fish tank is also largely dependent on the type of tank and fish you have inside, and how dirty the tank is.

Cleaning your fish tank is not a daunting task, all you need is a bottle of vinegar. This cleaner can clean aquarium glass thoroughly, anyway, you should all these 5 steps above for your fish’s safety.

How long to wait to put fish in tank after cleaning?

After the completion of disinfecting fish tank gravel for about 24 hours, you can put your fish back in the aquarium.

Why 24h? 24 hours from the completion of cleaning is the time for friendly bacteria to grow. This is also the time to make water suitable for your pet fish.

In many cases, you may find dead fish after cleaning tank, so it’s important to wait.


It’s really important to disinfect aquarium, especially after disease of the dead fish was revealed. As we said, fish corpses will cause many problems if you don’t handle them quickly, but it’s crucial to know how to sterilize fish tank after fish died in the right way.

Just simple steps but it can help you maintain a perfect aquarium. Follow the instructions right now!